1. Field of the Invention
This invention relates to medical devices and more particularly to an improved apparatus and method for inserting a medical device into a patient.
2. Background of the Invention
The prior art has known of various apparatuses and methods for introducing a medical device into a patient. These medical devices include cardiovascular catheters, catheter tubes, pacemaker electrodes or other medical devices that are inserted into a vein or artery of the patient.
One popular method was the Seldinger technique which utilized an apparatus comprising a dilator and a sheath. The dilator was formed from a rigid plastic tubular material terminating in a tapered tip. The sheath was formed from a flexible plastic material with a scored line extending along the length of the sheath. The sheath was carried on the dilator in a sliding relationship.
A puncture was made in the patient with a needle attached to a syringe. A flexible guide wire was passed through the needle into the patient and the needle and syringe were removed from the patient. The dilator and carried sheath was moved along the flexible guide wire into the original incision for opening or dilating the original incision and for positioning the dilator and the carried sheath within the vein or artery of the patient.
After the dilator and carried sheath was positioned in the desired region of the patient, the guide wire and the dilator were removed leaving the sheath positioned within the tissue. An internal bore of the sheath provided a conduit for introducing the medical device into the tissue and for positioning the device thereby. After the medical device was properly positioned within the tissue, the sheath was withdrawn from the tissue.
In many cases, the sheath was removed by peeling away the sheath from the medical device along the scored line extending along the length of the sheath. The device was positioned within the tissue in a simple and efficient manner.
Various forms of the dilator and the sheath apparatuses are available to the prior art. The following U.S. Patents are representative of some of the dilator and the sheath apparatuses for introducing a medical device into a patient.
U.S. Pat. No. 1,064,307 to Fleming discloses a sheath comprising a longitudinally divided body portion, a central fluid passage in the body portion, having a plurality of discharge openings communicating with the central passage and means for interlocking the longitudinally divided body portions. The means comprises dovetailed interlocking portions in the discharge end of the divided body portions, and segmental portions at the receiving end adapted to be inserted into a locking coupling.
U.S. Pat. No. 2,566,499 to Richter discloses an expansible needle assembly comprising an elongated tubular needle having one end substantially pointed and having at its opposite end an enlargement of rectangular cross-sectional shape provided with a counterbore. The needle is longitudinally divided into two substantially identical parts. A U-shaped bracket receives the enlarged portion of the needle means attaching one part of the needle to one leg of the bracket. The other leg of the bracket has a screw threaded aperture therein, a thumbscrew threaded through the aperture, and means rotatably connecting the thumbscrew to the other part of the needle at the end of the thumbscrew adjacent the other needle part.
U.S. Pat. No. 4,772,266 to Groshong discloses a dilator/sheath assembly for unstressed placement of catheter tubes into a body cavity of medical patients, which insure a stable axial relationship between concentrically superimposed sheath and dilator so that use is very facile for the medical attendant and insures a predetermined two-step gentle enlargement of a puncture site to accommodate unstressed placement of a catheter tube into a vein or artery through the puncture site and with minimal trauma to the patient.
U.S. Pat. No. 4,747,833 to Kousai et al. discloses a medical instrument-guiding tube for guiding a catheter or other rod-like medical instrument into a blood vessel. This guiding tube comprises a hollow tube body and at least one linear body integrally joined to the tube body along the longitudinal direction of the tube body. The plastic resin forming the tube body has a poor compatibility with that of linear body. The tube body and the linear body are engaged together through a complementary concave-convex engagement which can be disengaged with a reasonable force.
U.S. Pat. No. 4,840,613 to Balbierz discloses an improvement in a catheter assembly including a cannula, an inserter having a guide channel therethrough in which the cannula slidably fits and a hub structure with the cannula proximal end portion attached to the hub structure. The improvement includes a sheath having a longitudinal slit or weakened portion and being about the cannula between the inserter and the hub structure. A sheath stripping construction carried by the inserter strips the sheath from about the cannula as the cannula slides distally through the guide channel. A first lock member is carried by the inserter and an interlocking second lock member is located about the cannula between the inserter and the hub structure. The cannula is protected from contamination and from kinking and a positive lock serves to prevent its accidental withdrawal. A method of inserting a cannula using such an assembly is likewise set forth.
U.S. Pat. No. 5,098,392 to Fleischhacker et al. discloses a locking dilator and peel away introducer sheath assembly for preventing undesired rearward migration of a dilator within an introducer sheath to insure a proper longitudinal relationship. The dilator has secured to its proximal end a gripping clamp for holding securely the handle of the introducer sheath to accommodate placement of the dilator and introducer sheath into an appropriate location within a patient resulting in minimal tissue damage and trauma.
U.S. Pat. No. 5,154,703 to Bonaldo discloses a medical device which prevents the backflow of fluid therethrough and is particularly useful as a bloodless catheter assembly, that is, prevents the backflow of blood through the catheter by utilization of a self-closing valve carried in a hollow catheter housing to one end of which a catheter is fixed so as to provide a fluid passage through the catheter and catheter housing. The fluid passage in the catheter housing is sealed by a self-sealing valve element extending transversely across the passage upstream from the catheter. A hollow needle is held in the catheter housing downstream of and pointed at the valve element. Attachment of a fluid dispensing medical device to the other catheter housing end forces the valve element downstream onto the needle so as to pierce the valve element and open a fluid passage from the catheter housing upstream of the valve element through the hollow needle to the catheter. Removal of the medical device permits the resiliently biased valve element to move upstream away from the needle, thereby resealing and thus reclosing the fluid passage which extends through the hollow needle.
U.S. Pat. No. 5,125,904 and U.S. Pat. No. 5,312,355 to Lee discloses a splittable hemostatic valve and introducer sheath provided for introductions of leads or catheters through the valve and sheath combination into a vein or artery. Because of the hemostatic valve, this sheath can remain in the vein throughout the operation with the advantage of free lead exchange possibility and easier lead manipulation, especially in dual lead insertions, without bleeding, risk of air embolism or repeated sheath insertion related trauma for lead exchange. A side arm to the hemostatic valve cage provides continuous fluid drip in order to prevent clot formation in the lumen of the sheath. At the point in the operation where the introducer sheath and hemostatic valve must be removed from the lead or catheter, which must remain implanted, means are employed to split or separate the introducer sheath and valve apart so that the sheath and valve are removed from the implanted lead or catheter without the necessity of sliding either the sheath or valve over the free end of the lead or catheter. In this manner, any termination which may be provided on the free end of the lead or catheter, such as a terminal for connection to a pacemaker, will not interfere with the optional use of the introducer sheath and hemostatic valve.
U.S. Pat. No. 5,167,634 to Corrigan, Jr. et al. discloses a peelable sheath including a sheath formed of a flexible tube having a pair of separation lines arranged longitudinally on radially opposite sides of the tube to form a pair of peelable sheath portions, and a hub connector bonded to the proximal end of the sheath. A pair of wings are bonded to the proximal end of the sheath to facilitate separation. The hub connector and sheath are bonded by a web extending axially from a shoulder of the hub connector and including a pair of web tabs arranged on radially opposite sides of the hub connector. The web tabs are bonded to the sheath across respective separation lines, thereby preventing premature separation of the peelable sheath portions. The web also includes a pair of web support struts, arranged on radially opposite sides of the hub and rotated about 90xc2x0 relative to the web tabs, that are bonded to the respective wings to prevent premature separation of the hub connector from the sheath.
U.S. Pat. No. 5,380,292 to Wilson discloses an adjustable needle mechanism for gastrointestinal use in combination with an endoscope. The needle is received within a catheter or sheath and is movable between a first position in which it projects out of the catheter and a second position in which it is withdrawn into the catheter. A rotatable knob is provided to adjust the extent of projection of the needle when it is in the first position thereby eliminating any necessity to trim the end of the catheter.
U.S. Pat. No. 5,397,311 to Walker et al. discloses an apparatus provided for facilitating substantially bloodless insertion into and withdrawal from a patient""s body of a longitudinal member having a proximal end portion and having a distal end portion which is adapted to extend into the patient""s body. The apparatus comprises a longitudinally extending sleeve having proximal and distal end portions and defining a lumen extending there along. The longitudinal member is positioned along the lumen. The sleeve has a line extending longitudinally along it which is either split or splittable so that the sleeve can be separated along the line for removal from about the longitudinal member while the distal end portion of the longitudinal member remains extended into the patient. A valve structure serves for preventing blood flow through the lumen. An access is present for allowing substantially bloodless insertion and withdrawal of the longitudinal member through the lumen.
U.S. Pat. No. 5,584,820 to Gurmarnik discloses a set for spinal anesthesia that has a hollow introducer needle, a spinal needle introducible through the introducer needle into subarachnoid space, and a separate elongated hollow fixing element having a first portion which is fixable with the introducer needle, and a second portion surrounding exclusively the spinal needle and fixable with the spinal needle, so that the spinal needle is movable through the means between a plurality of positions and is fixed by the second portion to the fixing element in each of the positions.
U.S. Pat. No. 5,613,953 to Pohndorf discloses a transvenous lead introducer having an integral mechanical valve assembly which includes opposed coacting valve members that are operated by opposed handles. The handles of the valves are joined by rotatably link assemblies and are normally biased in a closed position by integrally formed bias springs.
Although the aforementioned apparatus has provided benefit to the medical community, the use of the combination of dilator and sheath suffered from certain inherent problems. Firstly, the sheath carried by the dilator formed a step or shoulder by the distal sheath end of the sheath at the juncture of the sheath and the dilator. The step or shoulder formed by the distal sheath end of the sheath hindered the insertion of the dilator within the tissue. Secondly, the step or shoulder formed by the distal sheath end of the sheath produced undesirable trauma and damage to the tissue as the dilator was inserted into the patient.
To overcome this difficulty some in the prior art had attempted to taper the distal sheath end of the sheath in order to reduce the shoulder formed thereby and to avoid the aforementioned disadvantages of the prior art. Unfortunately, the extent at which the distal sheath end of the sheath could be tapered was limited since such tapering reduced the mechanical strength of the distal sheath end of the sheath. For many years, this unsolved problem has existed in the medical art.
Therefore it is an object of the present invention to provide an improved apparatus for inserting a medical device into a patient which overcomes the disadvantages of the inherent problems of the prior art.
Another object of this invention is to provide an improved apparatus for inserting a medical device into a patient having a smooth outer surface to eliminate all problems associated with the step or shoulder formed at the juncture of the dilator and the sheath of the prior art devices.
Another object of this invention is to provide an improved apparatus for inserting a medical device into a patient having a smooth outer surface to eliminate the step or shoulder formed at the juncture of the dilator and the sheath of the prior art devices.
Another object of this invention is to provide an improved apparatus for inserting a medical device into a patient wherein a sheath having a smooth outer surface functions to dilate the tissue of the patient.
Another object of this invention is to provide an improved apparatus for inserting a medical device into a patient which provides the same ease and use as found in the prior art devices.
Another object of this invention is to provide an improved apparatus for inserting a medical device into a patient which is substantially the same or a reduced cost from the prior art devices.
Another object of this invention is to provide an improved apparatus for inserting a medical device into a patient which can be sterilized in a same or similar fashion as the prior art.
Another object of this invention is to provide an improved apparatus for inserting a medical device into a patient including a novel device for interlocking the sheath with a hub assembly.
The foregoing has outlined some of the more pertinent objects of the present invention. These objects should be construed as being merely illustrative of some of the more prominent features and applications of the invention. Many other beneficial results can be obtained by applying the disclosed invention in a different manner or modifying the invention with in the scope of the invention. Accordingly other objects in a full understanding of the invention may be had by referring to the summary of the invention, the detailed description describing the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.
The present invention is defined by the appended claims with specific embodiments being shown in the attached drawings. For the purpose of summarizing the invention, the invention relates to an improved apparatus for inserting a medical device into a patient. The improved apparatus comprises an obturator defining a distal obturator end. A sheath has an internal bore terminating at a distal sheath end. The internal bore of the sheath receives the obturator with the obturator supporting the sheath for enabling the sheath to be inserted within the patient. The obturator is advanced relative to the sheath to fracture the distal sheath end. The obturator is removable from the sheath for enabling the medical device to be inserted through the sheath to enter into the patient. The sheath is removable from the patient while the medical device remains within the patient.
In a more specific embodiment of the invention, the internal bore of the sheath receives the obturator in a sliding engagement with the substantially rigid obturator supporting the substantially flexible sheath for enabling the substantially flexible sheath to be inserted within the patient. The distal sheath end of the sheath has a sheath endwall at least partially enclosing the distal sheath end of the sheath. The distal obturator end of the obturator fractures the sheath endwall upon advancement of the obturator relative to the sheath.
In one embodiment of the invention, the obturator extends between the distal obturator end and a proximal obturator end with the distal obturator end having an external obturator taper. The sheath extends between the distal sheath end and a proximal sheath end. The distal sheath end has an internal sheath taper and an external sheath taper. The internal sheath taper of the distal sheath end conforms to the external obturator taper for supporting the distal sheath end for enabling the external sheath end to be inserted within the patient. The external obturator taper of the obturator fractures the sheath endwall upon advancement of the obturator relative to the sheath.
In another embodiment of the invention, the apparatus includes a hub assembly for attaching the obturator relative to the sheath for enabling the sheath to be inserted within the patient. The hub assembly detaches the obturator relative to the sheath for permitting advancement of the obturator relative to the sheath to fracture the distal sheath end. The hub assembly may include a removable coupling for attaching the obturator relative to the sheath to position the tapered distal obturator end adjacent to the tapered distal sheath end. The removable coupling is removable for permitting limited advancement of the obturator relative to the sheath to fracture the distal sheath end.
In the alternative, the hub assembly includes a threaded member for attaching the obturator relative to the sheath to position the tapered distal obturator end adjacent to the tapered distal sheath end. The threaded member permits limited advancement of the obturator relative to the sheath to fracture the distal sheath end.
The sheath may include a frangible region defined in the sheath for enabling the sheath to be removed from the patient and from the medical device while the medical device remains within the patient. Preferably, the frangible region extends to the external sheath taper for facilitating the fracture of the distal sheath end upon the advancement of the obturator relative to the sheath.
The foregoing has outlined rather broadly the more pertinent and important features of the present invention in order that the detailed description that follows may be better understood so that the present contribution to the art can be more fully appreciated. Additional features of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.